This project seeks to optimize a promising magneto-nanosensor technology for use in cancer diagnosis. By adapting a common technology from the computer disk drive industry, this simple device enables researchers to simultaneously detect multiple proteins, or biomarkers, at ultra low concentrations in biological fluids. The abundance and change over time of several of these biomarkers, when taken together, can be a powerful diagnostic tool. At this time, the tools required to measure these biomarkers, such as mass spectrometry or ELISA immunoassays, are slow, expensive, difficult to use, and often not very reproducible. In addition, many interesting biomarkers are present at such low concentrations that they simply cannot be detected with any but the most sophisticated and involved methods. The technology under development combines the advantages of high sensitivity, ease of use, rapid quantification, and low cost. These drastic improvements are possible in part due to the use of extremely sensitive giant magnetoresistive (GMR) sensors, and also because there are no natural magnetic signal sources in a blood sample, which results in a very low background signal. Additionally, these sensors have been modified to detect only those magnetic nanoparticle labels which are actually bound to the sensors - unbound labels floating nearby are almost completely ignored. That means that, unlike most other assay technologies, it is not necessary to remove the excess labels to determine the result. This allows the assay to be partially or completely wash-free, which again greatly increases the sensitivity and ease of use. Furthermore, no laser or complex optics are required because the signal is a simple change in electrical resistance of the sensor. This means that the ancillary instrumentation can be very simple and cost-efficient. With an initial focus on lung cancer, where there are no effective methods for early detection of the disease, researchers are attempting to validate a panel of six biomarkers that have been associated with asymptomatic lung cancer. The long term goal is to have a diagnostic test that allows doctors to diagnose patients when they are still in Stage I and face survival rates of 70-80%, as opposed today's situation where most patients don't get diagnosed until they reach Stage IIIB or IV and face less than a 10% chance of survival.